title: Suppression of heregulin β signaling by the single N-glycan deletion mutant of soluble ErbB3 protein.
abstract: Heregulin signaling is involved in various tumor proliferations and invasions; thus, receptors of heregulin are targets for the cancer therapy. In this study we examined the suppressing effects of extracellular domains of ErbB2, ErbB3, and ErbB4 (soluble ErbB (sErbB)) on heregulin β signaling in human breast cancer cell line MCF7. It was found that sErbB3 suppresses ligand-induced activation of ErbB receptors, PI3K/Akt and Ras/Erk pathways most effectively; sErbB2 scarcely suppresses ligand-induced signaling, and sErbB4 suppresses receptor activation at ∼10% efficiency of sErbB3. It was revealed that sErbB3 does not decrease the effective ligands but decreases the effective receptors. By using small interfering RNA (siRNA) for ErbB receptors, we determined that sErbB3 suppresses the heregulin β signaling by interfering ErbB3-containing heterodimers including ErbB2/ErbB3. By introducing the mutation of N418Q to sErbB3, the signaling-inhibitory effects were increased by 2-3-fold. Moreover, the sErbB3 N418Q mutant enhanced anticancer effects of lapatinib more effectively than the wild type. We also determined the structures of N-glycan on Asn-418. Results suggested that the N-glycan-deleted mutant of sErbB3 suppresses heregulin signaling via ErbB3-containing heterodimers more effectively than the wild type. Thus, we demonstrated that the sErbB3 N418Q mutant is a potent inhibitor for heregulin β signaling.
authors.affiliation: From the Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.
authors.forename: Motoko
authors.initials: M
authors.lastname: Takahashi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Wada
authors.forename: Michiko
authors.initials: M
authors.lastname: Tajiri
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ariki
authors.forename: Rina
authors.initials: R
authors.lastname: Takamiya
authors.forename: Chiaki
authors.initials: C
authors.lastname: Nishitani
authors.forename: Motoko
authors.initials: M
authors.lastname: Araki
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Taniguchi
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kuroki
mesh_terms: D019943:Amino Acid Substitution; D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000077341:Lapatinib; D020935:MAP Kinase Signaling System; D020125:Mutation, Missense; D020890:Neuregulin-1 / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D011799:Quinazolines / Q000494:pharmacology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism*; D066247:Receptor, ErbB-4
chemical_list: D000970:Antineoplastic Agents; D066246:ErbB Receptors; D000077341:Lapatinib; D020890:Neuregulin-1; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D066247:Receptor, ErbB-4; C094131:NRG1 protein, human; C508053:ERBB2 protein, human; C581292:ERBB3 protein, human; C587689:ERBB4 protein, human
keywords: Epidermal Growth Factor Receptor (EGFR); Glycosylation; Growth Factors; Mass Spectrometry (MS); Receptors